A long term study of patients with oligodendrogliomas. Follow-up of 50 cases, including Dr. Harvey Cushing's series

[Rare tumors of the lateral ventricle. Review of the literature]

Metastases of lateral ventricle (LV) are attached to choroidal plexus. Primary source is cancer of kidney. Two thirds of patients are male. Oligodendrogliomas occur in young females. Signs of increased intracranial pressure are a constant feature. These tumors are found in anterior portion of the LV with severe enhancement and clumped calcifications. Treatment is surgical. Cavernomas have a preponderance of rapid growth with a bleeding revelation. Seizures are rare. Rebleeding is frequent and justifies a surgical treatment. Schwannomas are a rare entity in which the majority of patients are very young. MRI shows calcifications, cystic components and a strong enhancement. They are limited to sporadic cases, never associated with neurofibromatosis. Arachnoid cysts are located in the atrium and/or in the occipital horn. Patients are young (mean age < 40 years). MRI demonstrates an intracystic lesion with signal intensity similar to the CSF. Best treatment is an endoscopic fenestration. Epidermoid cysts occur in third decade. These pearly tumors appear isointense or a little hyperintense on T1-weighted imaging, very characteristic. They are enhanced after gadolinium injection and appear strongly hyperintense on T2-weighted imaging. An incomplete removal with a thorough long-term follow-up is necessary. Cavernomas of LV are hyperintense on T1- and T2-weighted imaging. They have a bleeding risk of 25 to 45%. Therefore, they must be operated.

Is there a place for radiotherapy in low-grade gliomas?

The optimal management of supratentorial low-grade glioma remains controversial, and only limited definitive data is available to guide recommendations. Treatment decisions have to take into account both the management of symptoms and of tumour control, and must balance the benefits against the potential for treatment-related complications. Overall outcome is more dependent on patient and tumour-related characteristics such as age, tumour grade, histology and neurological function than treatment. From the pooled analysis of 2 randomized EORTC trials a prognostic score has been derived, median survival is varying from 3.2 to 7.8 years. Radiation therapy is usually the primary treatment modality; however its benefit on initial tumour control may be outweighed by potential late toxicity. To date only 4 large randomized trials in patients with low-grade glioma have been reported. It allows concluding that early radiotherapy does not improve overall survival and supports an initially expectative approach. Similarly, higher radiation doses above 45-50 Gy (fractions of 1.8-2.0 Gy) do not confer a better outcome but may be associated with increased toxicity. The adjuvant use of PCV-chemotherapy in high-risk patients also failed to improve progression-free and overall survival. An ongoing large randomized EORTC/NCIC trial is investigating the primary treatment with temozolomide chemotherapy versus standard radiotherapy in patients "at need for treatment". Tumour material will be collected in all patients, which ultimately may allow identifying on a molecular basis patients for whom one or another treatment strategy may fit best. Irrespective of new chemotherapeutic agents, radiotherapy is also evolving. Highly conformal techniques based on modern imaging as co-registered MRI scans, limiting the amount of normal tissue irradiated without compromising tumour control, will be the future approach in order to reduce neurotoxicity.

Radiotherapy in low-grade gliomas: pros

Although surgery is generally accepted as an important initial treatment in patients with low-grade gliomas, the role of postoperative radiotherapy (RT) is the subject of ongoing controversy. What is the most appropriate timing of RT? Is it best to deliver RT immediately after surgery or to watch and wait until disease progression? Numerous retrospective studies have shown that immediate postoperative RT provides a survival benefit. A recently published prospective study conducted by the European Organisation for Research and Treatment of Cancer has also shown that immediate postoperative RT significantly improved 5-year progression-free survival, but overall survival was not improved. Given the uncertainty about the overall survival benefit of immediate RT and the potential for radiation-induced toxicity, it is important to consider prognostic factors when selecting patients. Subgroups of patients with poor prognostic factors are more likely to benefit from immediate postoperative RT. Available data indicate that a carefully balanced therapeutic approach is needed to optimize treatment outcomes in patients with low-grade gliomas. Patients with more aggressive disease and a high risk of malignant transformation will likely benefit from immediate RT, whereas patients with low-risk disease, particularly oligodendrogliomas, can reasonably be observed. However, one cannot exclude the possibility that delaying RT may result in a worse long-term clinical outcome.

Radiation therapy for incompletely resected supratentorial low-grade glioma in adults

In this review on current concepts in radiation therapy in the treatment of incompletely resected supratentorial low-grade glioma, a number of important issues are discussed. They include indication for radiation therapy, timing (early vs delayed), dose response issue, impact of modern neuroimaging, 'optimal' treatment fields, impact of histology, new and promising approaches as well as quality of life in this disease are also discussed. This disease remains a focus of investigations in neuro-oncology owing to the fact that a number of questions discussed in the text are still far from being optimally addressed and answers are, therefore, lacking. New studies and more patients are needed to get more insight into this disease.

Parotid gland metastases of two uncommon neoplasms with low metastatic potential

Oligodendrogliomas are uncommon intracranial glial tumours in which extracranial spread is only rarely reported. Similarly, both intracranial and ocular medulloepitheliomas are also rare, with metastatic spread from the ocular neoplasm being less common than its intracranial counterpart. We report cases of an intracranial oligodendroglioma and an ocular medulloepithelioma both of which metastasised to the parotid gland. To our knowledge these are only the second oligodendroglioma and the third ocular medulloepithelioma to be reported as metastasising to this site.

Radiation and chemotherapy improve outcome in oligodendroglioma

PURPOSE

Oligodendroglioma is a rare central nervous system tumor which may occur in pure or mixed histology. This scarcity results in difficulty in defining optimal management, mainly due to a lack of outcome analysis. Results are further complicated because the reported series include patients treated before megavoltage radiation or computed tomographic (CT) scan development. This makes extrapolation of outcome difficult to apply to modern-era patients. We report results obtained by current treatment and evaluation.

METHODS AND MATERIALS

Outcome of all 38 patients (age 5-70 years) pathologically diagnosed between 1975 and 1993 were reviewed. Pure lesions were seen in 14 cases, of which three were anaplastic. The remainder had mixed tumors, of which six contained anaplastic astrocytic elements. Each patient had undergone maximal debulking surgery, but all remained with residual disease on postoperative CT.

RESULTS

For nonanaplastic lesions, no local failure was seen in any patient receiving postoperative radiation (60 Gy) and chemotherapy (vincristine, procarbazine, and carmustine). Follow-up ranged from 28 to 240 months (median 125; N = 6). No postoperative therapy or chemotherapy alone resulted in local failure in all nine patients at risk [time to failure (TTF): 2-40 months; median 25]. Radiation alone in doses of 50 Gy at 2 Gy per day resulted in all six patients failing (TTF: 12-52 months; median 36). Achieving 60 Gy at 2 Gy a day allowed five of eight patients to remain disease free (disease-free survival: 24-160 months; median 66), with three failing at 26, 40, and 60 months. All lesions containing anaplastic elements underwent postoperative radiation therapy (60 Gy) and chemotherapy, with five of nine patients alive and well (median disease-free survival: 48 months; range 28-120).

CONCLUSION

The combination of radiation and chemotherapy increases local control of oligodendroglioma whether they contain pure, mixed, or anaplastic histology. Radiation alone may offer good local control as long as 60 Gy is delivered. Chemotherapy alone appears to delay TTF and may be useful for pediatric patients.

Prognostic factors in oligodendrogliomas

An outcome analysis was performed on 96 patients with pure cerebral oligodendrogliomas operated in the 30-year period 1962 to 1991. The most important predictive prognostic factors were youth and no neurological deficit, demonstrated as a median survival for the group younger than 20 years of 17.5 years and for the group older than 60 years of 13 months. The group without neurological deficits had a 5-years survival of 43 per cent while the group with deficits had a 5-years survival of 5 per cent. The 5-years survival for oligodendroglioma of grade II was 46 per cent and for grade III 10 per cent. We found no effect of radiotherapy on survival, neither in the whole material or in any subgroup.

Prognostic value of the proliferation-related antigen Ki-67 in oligodendrogliomas

BACKGROUND

In various neoplasms expression of the proliferation-related Ki-67 antigen has successfully been linked with parameters of progression of disease. While a definite grading scheme for oligodendrogliomas has still not been agreed upon, any parameter of tumor proliferation that might be helpful in predicting clinical outcome should be evaluated.

METHODS

The expression of the proliferation related nuclear antigen Ki-67 (MIB-1 monoclonal antibody) was investigated in a series of 108 verified oligodendrogliomas, and the percentages of immunoreactive cells were compared with the survival times of the patients. Using multivariate analysis the prognostic value of MIB-1 labeling index (LI) was assessed taking into account age, tumor site, grade, and mitotic index (MI).

RESULTS

Patient's age, tumor site, grading according to the grading scheme by Smith, MI and MIB-1 LI were all significantly related to survival. Whereas in a multivariate analysis, age, site, grade and MIB-1 LI had independent prognostic significance, MI failed to add significant prognostic value.

CONCLUSIONS

The MIB-1 LI is an important addition to histopathologic grading for predicting clinical outcome of patients with oligodendrogliomas. The MIB-1 LI adds prognostic information independent of patient's age, tumor site and grade. The MI might be incorporated into a grading scheme for oligodendrogliomas, but is not by itself an additional prognosticator.

Low-grade gliomas of the cerebral hemispheres in children: an analysis of 71 cases

Low-grade gliomas constitute the largest group of cerebral hemispheric tumors in the pediatric population. Although complete tumor resection is generally the goal in the management of these lesions, this can prove difficult to achieve because tumor margins may blend into the surrounding brain. This raises several important questions on the long-term behavior of the residual tumor and the role of adjuvant therapy in the management of these lesions. To examine these issues, the authors reviewed their experience in 71 children with low-grade cerebral hemispheric gliomas who were treated at their institution between 1956 and 1991 and assessed the relationship between clinical, radiographic, pathological, and treatment-related factors and outcome. Only seven patients in the series died, one from perioperative complications, five from progressive disease, and one (a child with neurofibromatosis) from a second neoplasm. For the 70 patients who survived the perioperative period, overall actuarial survivals at 5, 10, and 20 years were 95%, 93%, and 85%, respectively; progression-free status was maintained in 88%, 79%, and 76%, respectively. On univariate analysis, the factor that was most strongly associated with both overall and progression-free survival was the extent of tumor resection (p = 0.013 and p = 0.015, respectively). A relationship between extent of resection and progression-free survival was present both in patients with pilocytic astrocytomas (p = 0.041) and those with nonpilocytic tumors (p = 0.037). Histopathological diagnosis was also associated with overall survival on univariate analysis; poorer results were seen in the patients with nonpilocytic astrocytoma compared to those with other low-grade gliomas, such as pilocytic astrocytoma, mixed glioma, and oligodendroglioma (p = 0.021). The use of radiotherapy was not associated with a significant improvement in overall survival (p = 0.6). All three patients who ultimately developed histologically confirmed anaplastic changes in the vicinity of the original tumor had received prior radiotherapy, 20, 46, and 137 months, respectively, before the detection of malignant progression. In addition, children who received radiotherapy had a significantly higher incidence of late cognitive and endocrine dysfunction than the nonirradiated patients (p < 0.01 and 0.05, respectively). The authors conclude that children with low-grade gliomas of the cerebral hemispheres have an excellent overall prognosis. Complete tumor resection provides the best opportunity for long-term progression-free survival. However, even with incomplete tumor excision, long-term progression-free survival is common.(ABSTRACT TRUNCATED AT 400 WORDS)

Cerebral oligodendroglioma: prognostic factors and life history

The records of 137 patients with supratentorial oligodendroglioma treated surgically between 1953 and 1986 were reviewed. The tumors were rated histologically benign or malignant. In the 105 patients followed up with a minimum observation time of 5 years to December 1991, the mean postoperative survival was 90.2 months (standard error, 9), the median 64 months (standard error, 9.6), the 5-year survival rate 52.4%, and the 10-year survival rate 24%. Sixteen possible prognostic factors, broken down into two or more variables each, were considered in the survival study on univariate methods (5-year survival rate, survival curves, and Cox's hazard function) and on multivariate analysis according to Cox's stepwise proportional hazards model. The latter showed that variables correlated positively with survival were benign histological findings (P, 0.000), postoperative radiation therapy (P, 0.004), and time of operation from 1977 to 1986 (P, 0.044) in 105 patients of the whole series, and period of surgery from 1977 to 1986 (P, 0.000), subtotal or total surgical resection of the tumor (P, 0.001), and radiation therapy (P, 0.005) in the subgroup of 79 patients operated on for benign tumors. However, the most interesting point to emerge from the study was the relevance of admission clinical status to the survival of patients who did not receive radiation therapy and to the prognostic response of those who did. Of the 40 patients with seizures and negative neurological status--Clinical Syndrome A--the 10 who did not receive radiation therapy had survived as long as the 30 who did (5-year survival rate, 80 versus 67%; P, not significant; median survival, 122 versus 85 months; Breslow and Mantel-Cox P, not significant), whereas of the 65 patients with intracranial hypertension and/or neurological deficits--Clinical Syndrome non-A--the 18 who did not receive radiation therapy had short survival times, and the 47 who did fared significantly better (5-year survival rate, 11 versus 53%; P, 0.002; median survival, 32 versus 64 months; Breslow and Mantel-Cox P, 0.000). These findings were not significantly affected by the exclusion of malignant neoplasms and in the group of benign tumors, in which the histological characteristics have not been found to be significantly different between those with A and those with non-A clinical syndrome, did not depend on different frequencies of subtotal or total tumor removal.(ABSTRACT TRUNCATED AT 400 WORDS)

The role of postoperative irradiation in the treatment of oligodendroglioma

PURPOSE

Controversy regarding the role of adjuvant radiation therapy for the treatment of oligodendroglioma continues to exist. To better define the utility of postoperative irradiation for this tumor, the experience at the University of Washington was retrospectively examined.

METHODS AND MATERIALS

The histologic samples of 63 patients given the diagnosis of oligodendroglioma were reviewed by a panel of neuropathologists and 41 were classified as pure oligodendroglioma. The two treatment groups included 14 patients treated with surgery only and 27 who received surgery and postoperative radiation and were analyzed using univariate and multivariate analysis with respect to prognostic factors, freedom from relapse, and survival.

RESULTS

Univariate statistical analysis of 14 clinical variables showed that a poorer prognosis was associated in patients with high cell density (p = .008), necrosis (p = .017), hemiparesis (p = .026), and papilledema (p = .091), while patients presenting with seizures had a better prognosis (p = .0096). Multivariate analysis showed necrosis (p = .001) and hemiparesis (p = .02) to be associated with decreased survival. Multivariate and univariate analysis of the treatment groups found them to be homogenous with respect to prognostic factors. Survival times were significantly longer in the group treated with postoperative irradiation (median survival time 84 vs. 47 months, p = .032). The 5 and 10 year survival rates were 83% and 46%, respectively, for the irradiated patients compared with 51% and 36% for those treated with surgery alone. Freedom from tumor recurrence times were also longer in irradiated patients (median relapse free time 79 vs. 42 months, p = .01).

CONCLUSION

Based on the results of this study, we recommend continuing the practice of treating oligodendroglioma with postresection irradiation until a prospective multicenter clinical trial is conducted to thoroughly evaluate the role of postoperative irradiation in the treatment of this tumor.

The prognostic implications of histologic classification and bromodeoxyuridine labeling index of mixed gliomas

To clarify the biological and clinical behavior and prognosis of mixed gliomas, 47 patients underwent intraoperative bromodeoxyuridine (BrdU) labeling studies. The mean age was 27.8 years at symptom onset and 31.8 years at labeling (median, 36 years). Forty-five tumors were supratentorial, 30 were frontal, and two were cerebellar; 16 were recurrent at labeling. The median labeling index (LI) was 1% (range, < 1 to 15.1%). Forty-six tumors has oligodendroglial and astrocytic elements, and one had astrocytic and ependymal elements. The median LI was 4.4% in recurrent tumors and < 1% in primary tumors. A higher BrdU LI correlated with an increased risk of recurrence and a shorter time to recurrence. During a median follow-up of 16 months, four patients died; each had a BrdU LI > or = 4.4%. The median time to recurrence was 4.5 months for tumors with BrdU LI's > 5% but was not reached for tumors with LI's < 5% (p < 0.003). The histologic grade of the oligodendroglial component correlated with the median time to recurrence (8 months for Smith Grade C tumors, not reached for Smith Grade B tumors; p < 0.05); there were too few cases to evaluate the median times to recurrence of Smith Grade A and Grade D tumors. The median time to recurrence was not reached for any astrocytic grade, and there were no significant differences in the Kaplan-Meier survival curves. These findings suggest that the BrdU LI and the grade of the oligodendroglial component of mixed gliomas have prognostic significance.

Radiotherapy for supratentorial low-grade gliomas: results and prognostic factors with special focus on tumour volume parameters

From 1973 to 1990, 67 patients with a diagnosis of low-grade glioma were treated in our hospital. Overall survival was analysed as well as the influence of patient, tumour- and treatment-related factors with special focus on tumour volume parameters. Our study group included 49 patients treated by surgery and post-operative radiotherapy (RT) (40 patients) or post-biopsy irradiation alone (9 patients). Total or almost total resection was performed in 16 patients; partial excision was done in 24. With the available pre-surgery and pre-RT CT-scan and/or MRI images we were able to calculate tumour volumes by measuring the largest tumour dimensions in the three axes D1, D2, D3 and by assuming an ellipsoidal growth (i.e., tumour volume = D1D2D3 pi/6). RT was delivered to involved regions: either the residual tumour volume or the tumour bed. The median RT dose was 56 Gy (45-60, range). The 60- and 90-month overall survival (Kaplan-Meier) was 79% and 67%, respectively. Female sex, > 70% Karnofsky (Kf) score, oligodendroglioma and < 71 cm3 (approximately 5 cm diameter sphere) tumour residuals before RT were associated with better overall survival rates (p < 0.05, log-rank). However, a Cox proportional hazards model showed that only the histological subtype and Kf significantly determined the patients' outcome: 60-month overall survival of 100%, 62%, 83% and 64% for oligodendrogliomas, mixed oligo-astrocytomas and grade-I and grade-II astrocytomas, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult supratentorial tumors

MR imaging has represented a significant advance in the diagnosis and management of adult supratentorial neoplasms, and indeed MR has become the modality of choice for the initial diagnosis and follow-up in these cases. It is clear that the overall sensitivity has increased significantly, due to both the use of MR itself and to the implementation of IV contrast agents. It appears that some inroads have been made with regard to specificity, but significant overlap still exists in the imaging appearance of many of these entities. A thorough knowledge of neuroanatomy, pathophysiology, and neuropathology aid markedly in the imaging diagnosis of these processes.

[Oligodendroglioma of the cerebellopontine angle: 16 years' course. Review of the literature and considerations on the pathology]

The authors after a meticulous bibliography research have found 43 cases of oligodendrogliomas in the posterior fossa. Out of these 43 cases they came to know that two of them were located in the cerebello pontine angle. The authors describe one more case of this pathology in this rare localization and call attention to the fact that the evolution of this case has been confirmed during the last sixteen years.

Familial glioma: a report of glioblastoma in identical twins and oligo-astrocytoma in siblings

The authors report two pairs of siblings who had intracranial gliomas. One pair of identical twins had glioblastomas and two siblings had mixed oligo-astrocytomas. Genetic influences in the aetiology of glioma are discussed.

Lack of histopathological correlation of malignant ependymomas with postoperative survival

It is widely believed that an important determinant of clinical behavior and prognosis in patients harboring an ependymoma is the histological grade of malignancy of the tumor. Excluding from the present analysis examples of ependymoblastoma (a highly cellular, embryonal tumor occurring in children, with a notably poor prognosis and a tendency to subarachnoid spread), an attempt was made to correlate 15 cases of histologically malignant ependymoma with clinical recurrence and postoperative patient survival times. Ten patients (67%) were alive from 15 months to 14 years after surgery (median survival time 8.8 years); one patient had a histologically benign recurrence 11 years after surgical resection. Five patients (33%) died from a local recurrence of their tumor; their postoperative survival times ranged from 13 months to 6 years (median 2.5 years). The prognosis of malignant ependymomas is therefore highly variable. No correlation was possible between the tumor's histological features, site, or likelihood of recurrence. This lack of clinicohistopathological concordance contrasts with the known correlations that exist in astrocytomas.

Oligodendroglioma. A comparison of two grading systems

In order to compare the grading system for oligodendrogliomas described by M.T. Smith (1983) with the conventional grading system according to Kernohan (1938), specimens from 72 patients were graded according to both systems, and survival times of the patients were compared. Survival rates decline in older patients. No interaction between the age of the patient and the degree of the tumor was found. No influence of localization of the tumor on survival was found. Similar to the system of Kernohan, the grading system of Smith distinguishes between only three groups of patients with significantly different survival times. In Smith's Grade A and Kernohan's Grade 1 the longest survivals are found; while in Smith's Grade D and Kernohan's Grade 4 the shortest survivals are found. Smith's Grades B and C as well as Kernohan's Grades 2 and 3 were intermediate with respect to the survival times of the patients and did not significantly differ from each other. With the independently significant features (cell density, pleomorphism, and necrosis) evaluated according to simple on-off scoring, and with the reduction from four grades to three, the grading system according to Smith would provide a simple and good, concise grading system for oligodendrogliomas of the brain.

Treatment of oligodendrogliomas with or without postoperative irradiation

The authors have reviewed the treatment results in 42 patients with intracranial oligodendroglioma treated from 1940 through 1983 at the University of California, San Francisco. Two patients who died postoperatively were excluded from analysis. Eleven patients had mixed tumors, with a minor astrocytic component. The overall survival rates for the 29 patients with pure oligodendroglioma were 61% and 33% at 5 and 10 years, respectively; these rates for the 11 patients with mixed tumors were 57% and 38% at 5 and 10 years, respectively. The 10-year survival rate for 14 patients with pure oligodendroglioma who received greater than 45 Gy irradiation was 56% versus 18% for 11 patients who did not receive postoperative irradiation (p = 0.09). Nine patients with mixed tumor who received more than 45 Gy postoperatively had survival rates similar to those for the 14 patients with pure tumors irradiated with more than 45 Gy (p = 0.89). All patients who died of their tumor had evidence of intracranial recurrence. One patient, who did not receive initial postoperative irradiation, also had clinical and myelographic evidence of spinal seeding. All five patients examined postmortem had tumor recurrence at the primary site; one patient also had intraventricular seeding. Six of the 10 patients with pure oligodendroglioma who had a repeat biopsy at the time of tumor recurrence or at postmortem examination showed histological progression to an anaplastic astrocytoma or glioblastoma multiforme. Based on this study, adult patients with pure or mixed oligodendroglioma currently are treated with partial-brain irradiation to a dose of about 60 Gy. In general, children are treated with partial-brain irradiation to about 50 Gy.

Oligodendroglioma. An analysis of the value of radiation therapy

The role of radiation therapy in the treatment of supratentorial oligodendrogliomas is controversial. To evaluate the role of radiation therapy, the Duke University Medical Center series was retrospectively analyzed. Clinical history, radiation dosages, and pathologic materials were reviewed. Seventy-one patients were identified as having histologically proven oligodendroglioma. Analysis of the patient population demonstrated it to be similar in all major parameters to other populations previously reported in the literature. Multivariate statistical analysis of the demographic, clinical and radiographic variables of these patients showed that a poorer prognosis was associated with persons of increased age (P = 0.052) and black persons (P = 0.014), and in those with papilledema (P = 0.07), hemiparesis (P = 0.001), intellectual deficits (P = 0.0002), and necrosis (P = 0.041). All patients had a surgical procedure as first treatment while 18 and three patients, respectively, underwent a second and third surgical procedure. Thirty-seven patients had a subsequent course of radiotherapy. Univariate and multivariate statistical analysis comparing the patients treated with surgery alone those treated with surgery plus radiotherapy revealed no significant population or prognostic differences between the groups. The median times until clinical deterioration were 39 versus 27 months, the median times until documented tumor recurrence were 27 versus 28 months and the median survival times were 4.5 versus 5.2 years, for nonirradiated versus irradiated patients. These data, from a large and rigidly evaluated population, demonstrated no statistically significant difference in the symptom-free interval, time until tumor recurrence, or survival between the groups nor did radiation appear beneficial to any subgroup evaluated. The results suggest the need for a prospective clinical trial to evaluate the true role of radiation therapy in the treatment of this tumor.

Statistical analysis of clinicopathological features, radiotherapy, and survival in 170 cases of oligodendroglioma

The postoperative survival time of 170 nonrandomized patients treated for cerebral oligodendrogliomas in Norway from 1953 to 1977 was studied. Survival times were significantly prolonged if postoperative irradiation was performed in addition to surgery (median survival time 26.5 vs. 38 months, p = 0.039). In the group without postoperative radiotherapy, the 5-year rate of survival was 27% compared with 36% in the irradiated patients. The respective survival rates after 8 years were 14% versus 17%; thus, there was little effect on long-term survival. Irradiation appears not to be of benefit after "total" removal. Patients with partly resected lesions appeared to benefit from postoperative radiotherapy; the median survival period after subtotal tumor resection was 37 months with and 26 months without radiotherapy (p = 0.0089). The findings also indicate that irradiation doses between 40 and 50 Gy were as effective as doses between 50 and 60 Gy in increasing the patients' probability of surviving 5 years after subtotal tumor resection. Since the risk of radiation necrosis is proportional to the dose applied, the lower dose is recommended. These conclusions were also valid when adjustments were made for prognostically significant histological and clinical features.

Clinicopathologic correlations in the oligodendroglioma

To determine the prognostic significance of histologic variables in oligodendroglial neoplasms, the presence and degree of 15 such variables were correlated with postoperative survival rates in 71 patients. By univariate analysis, prognostically significant factors, in order of decreasing importance, were mitoses (log), necrosis, nuclear cytologic atypia, vascular hypertrophy, and vascular proliferation. When studied by stepwise regression, necrosis and the number of mitoses contained all of the prognostically useful information. When each of the five variables significant by univariate analysis was tested in the Cox model by adding a variable to the model containing the other four, necrosis was found to be the only independently significant variable. There were significant positive pairwise correlations between each of the five significant histologic variables except for cytologic atypia with necrosis. The only histologic variable with a significant association with older age was the number of mitoses. These results suggest that necrosis and, to a lesser extent, the mitotic count are features that, in the appropriate setting, can be used to identify the "anaplastic" oligodendroglioma.

Oligodendroglioma: an analysis of 42 cases

This paper presents the clinical and pathological data obtained from 42 patients with oligodendroglioma diagnosed over a 20 year period at Addenbrooke's Hospital, Cambridge. In all cases the diagnosis was established unequivocally by histological examination. The principal conclusions of this study were: (1) the outcome was not as favourable as anticipated, nine patients dying within 1 year of diagnosis, and only 10 patients surviving 5 years, (2) age at the time of diagnosis was the single most important prognostic factor, patients under 45 years at diagnosis having a significantly greater survival time than older patients, (3) two other factors had a significantly adverse effect on prognosis, namely the presence of a focal neurological deficit at the time of diagnosis and the presence of nuclear pleomorphism in the tumour when examined histologically, (4) although cells containing glial fibrillary acidic protein were demonstrated in almost every tumour, their number and distribution did not appear to influence the prognosis.

A clinicopathological study of 323 patients with oligodendrogliomas

All patients with oligodendrogliomas (554) from the repository of the Armed Forces Institute of Pathology were retrospectively analyzed. The pathological diagnosis was confirmed in 323 patients and each case was graded according to a previously established grading system. The clinical features of these 323 verified cases of oligodendroglioma are presented, analyzed, and compared with findings in previous studies. There is a significant age skew according to tumor grade, with 68% of patients with grade A tumors under 40 years and 83% of patients with grade D tumors over 40 years of age. Headache was the most common symptom, followed by seizure, visual loss, papilledema, paralysis, and dementia. No symptoms showed a statistically significant correlation with tumor grade. However, tumor grading allowed significant prognostic statements to be made. Attention is drawn to several often neglected symptoms of oligodendrogliomas: ataxia, hemorrhage, stroke, and cerebrospinal fluid spread. This is, to our knowledge, the largest clinicopathological study of oligodendrogliomas to date.

Oligodendroglioma: incidence and biological behavior in a defined population

The cases of 208 patients with histologically confirmed oligodendrogliomas were studied. The incidence represents 4.2% of all primary brain tumors diagnosed in the Norwegian population over a 25-year period. All of these tumors were cerebral and the majority affected the frontal lobe. The patients' median age at diagnosis was 47 years, with a range from 3 to 76 years; 6% of the oligodendrogliomas occurred in children. The median duration of symptoms before diagnosis was 20.5 months (mean 43 months). Plain skull x-ray films showed calcified deposits in 28% of the tumors. At operation, most of the tumors were poorly defined, without cyst formation, hematoma necrosis, or calcification. The median duration of disease from onset of symptoms until death was 14 months in nine untreated cases. In surgically treated oligodendroglioma patients the median survival time from onset of symptoms was 74 months. The median postoperative survival time was 35 months (mean 52 months). Tumor calcification, as seen on plain skull x-ray films, was associated with a significantly longer survival period. The surgical findings of gross necrosis, gross hypervascularity, and soft tumor consistency were all related to a shorter total duration of disease. Grossly well demarcated lesions were associated with a significantly longer postoperative survival. The length of postoperative survival correlated with the preoperative clinical status. The cumulative proportion of patients surviving 5 years was 0.342. The patient's age and sex did not have a statistically significant influence on survival time. The extent of surgical excision only seemed to play a role when the neurosurgeon considered that he had removed the whole lesion: these patients had a median postoperative survival period 14 months longer than the other oligodendroglioma patients. The ABO blood group of the oligodendroglioma patient was of prognostic value. In particular, patients with blood group A had a distinctly poorer prognosis than patients with O or B blood. The survival data from this unselected series indicate that cerebral oligodendrogliomas have a less favorable prognosis than has generally been believed.

Primary oligodendroglioma of the lateral ventricle with computed tomographic and positron emission tomographic evaluations

Two cases of primary intraventricular oligodendrogliomas are presented. Total excisions of well-demarcated large tumors in the lateral ventricle were successfully performed in young women by means of a frontal transventricular approach. An evaluation by computed tomography and positron emission tomography was attempted to obtain definite diagnosis of not only the location of the tumor but also the histologic grade of malignancy.

Grading of oligodendrogliomas

The purpose of this study was to determine the effectiveness of histologic grading of oligodendrogliomas in a retrospective study. 323 cases with adequate clinical information and confirmatory histological material were acquired from the files of the AFIP. A grading system was devised using the following criteria: endothelial proliferation, necrosis, nuclear/cytoplasmic ratio, cell density and pleomorphism. The grading system separated 23% of the cases into grade A, 49% into grade B, 22% into grade C and 6% into grade D. Statistical analysis showed that the grading system significantly correlated with survival (P less than or equal to 0.01). Median survival periods for each grade were as follows: grade A, 94 months; grade B, 51 months; grade C, 45 months; grade D, 17 months. Of the five factors comprising grade, only pleomorphism was significantly correlated with survival by itself (P less than or equal to 0.01). It is concluded that grading of this form of glioma can be an effective estimate of prognosis.

Supratentorial recurrences of gliomas. Morphological studies in relation to time intervals with oligodendrogliomas

On the basis of a three stage grading system we report 23 stage one recurrent oligodendrogliomas (O 1), and 29 stage two recurrent oligodendrogliomas (O 2). In the O 1 group after the first interval 15 became O 2 and 2 became glioblastomas. Twenty tumours of the O 2 group after the first interval were not changed, three became oligodendroglioma-astrocytomas stage 2, and six became glioblastomas. The time relation for the recurrent phase in the primary O 1 group is calculated as 42 months, and in the primary O 2 group as 22 months, but this is without significance. For the development of malignancy, especially for the change to glioblastoma, a prominent participation by transformed local astrocytes seems to be essential. Postoperative irradiation most probably does not favour malignant change. A prolongation of the expectation of life by radiotherapy is not noticed.

Late appearance of meningioma at the site of partially removed oligodendroglioma. Case report

A case is presented in which a meningioma and a glioma grew in the region where, 23 years before, a glial tumor had been partially removed and irradiated. The authors suggest that surgical trauma and ionizing radiation may have influenced the tumor's development.